Old Head aka Bernie is the mentor of the Grinto and the Combo ninos
Bernie like to teach caporera in a strict manner. But in his stone head form, he is quite the fun type. Despite how impatient Grinto was towards Bernie as a child, he stilled cared about his student.
Not much is said about Bernie, except for the flashbacks that relates to Grinto as a child (in episode Child Grinto). Bernie was an old man when Grinto was a child. Bernie dived in to save Grinto from being stuck in the divino world for eternity. He kicked the elephant divino (?) into the divino world then threw Grinto out of the portal back to the human world and turn into a stone head when he entered the divino world. He managed to get back to the human world but he remained a stone head for the rest of his life.